The role of multifunctional kinetics during early-stage silicon hydride pyrolysis: Reactivity of Si₂H₂ isomers with SiH ₄ and Si₂H₆

Kinetic parameters for the dominant pathways during the addition of the four Si₂H₂ isomers, i.e., trans-HSiSiH, SiSiH₂, Si(H)SiH, and Si(H₂)Si, to monosilane, SiH₄, and disilane, Si₂H₆, have been calculated using G3//B3LYP, statistical thermodynamics, conventional and variational transition state theory, and internal rotation corrections. The direct addition products of the multifunctional Si₂H₂ isomers were monofunctional substituted silylenes, hydrogen-bridged species, and silenes. During addition to monosilane and disilane, the SiSiH₂ isomer was found to be most reactive over the temperature range of 800 to 1200 K. Revised parameters for the Evans-Polanyi correlation and a representative pre-exponential factor for multifunctional silicon hydride addition and elimination reaction families under pyrolysis conditions were regressed from the reactions in this study. This revised kinetic correlation was found to capture the activation energies and rate coefficients better than the current literature methods.